Emulator

Game Name?

The Legend of Zelda: The Wind Waker and others.

What's the problem? Describe what went wrong.

Use any game with Deterministic Dualcore (GPU Sync fake-completion) that relies on EFB Access to CPU. The Legend of Zelda: The Wind Waker does this on the sun effect and requires no input whatsoever to test.
Framerate will tank when this happens in newer builds. This affects both movies and netplay, as well as anyone who sets deterministic dualcore for stability reasons (which happens, apparently.)

Is the issue present in the latest development version? For future reference, please also write down the version number of the latest development version.

The issue is present in 5.0-12088

Is the issue present in the latest stable version?

It is not present in 5.0

If the issue isn't present in the latest stable version, which is the first broken version? (You can find the first broken version by bisecting. Windows users can use the tool https://forums.dolphin-emu.org/Thread-green-notice-development-thread-unofficial-dolphin-bisection-tool-for-finding-broken-builds and anyone who is building Dolphin on their own can use git bisect.)

5.0-583 is the first broken version

If your issue is a graphical issue, please attach screenshots and record a three frame fifolog of the issue if possible. Screenshots showing what it is supposed to look like from either console or older builds of Dolphin will help too. For more information on how to use the fifoplayer, please check here: https://wiki.dolphin-emu.org/index.php?title=FifoPlayer

I do not know if this is an issue with Dolphin or simply a consequence of Deterministic Dualcore.
Issue was originally known, but the bisect hint was given to me by this thread - https://forums.dolphin-emu.org/Thread-solo-netplay-performance-tank

What are your PC specifications? (CPU, GPU, Operating System, more)

Core i7-6700K, GTX 1070, Windows 10, 256KB of RAM